- A
Cloud Functions
Why wrong: Cloud Functions is a serverless compute service, not an API for prediction.
- B
REST API
Why wrong: REST API is simpler but less efficient than gRPC for high-throughput.
- C
Cloud Pub/Sub
Why wrong: Pub/Sub is for asynchronous messaging, not real-time prediction.
- D
gRPC API
gRPC provides better performance for online prediction due to binary serialization and streaming.
Question 938 of 1,000
PMLE Serving and Scaling Models Practice Question
This PMLE practice question tests your understanding of serving and scaling models. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which API is recommended for high-throughput, low-latency online prediction requests to Vertex AI endpoints?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
gRPC API
gRPC API is recommended for high-throughput, low-latency online prediction requests to Vertex AI endpoints because it uses HTTP/2 for multiplexed streaming, binary serialization (Protocol Buffers), and supports bidirectional streaming, which reduces latency and improves throughput compared to REST. Vertex AI's prediction service natively supports gRPC for real-time inference, making it the optimal choice for latency-sensitive applications.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Cloud Functions
Why it's wrong here
Cloud Functions is a serverless compute service, not an API for prediction.
- ✗
REST API
Why it's wrong here
REST API is simpler but less efficient than gRPC for high-throughput.
- ✗
Cloud Pub/Sub
Why it's wrong here
Pub/Sub is for asynchronous messaging, not real-time prediction.
- ✓
gRPC API
Why this is correct
gRPC provides better performance for online prediction due to binary serialization and streaming.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that REST API is the default or only way to interact with cloud services, but the trap here is that for high-throughput, low-latency online predictions, gRPC is explicitly recommended over REST due to its performance advantages with Protocol Buffers and HTTP/2.
Detailed technical explanation
How to think about this question
gRPC leverages HTTP/2 features like multiplexing (multiple streams over a single connection), header compression, and server push, which drastically reduce per-request overhead. In Vertex AI, gRPC endpoints use the `google.cloud.aiplatform.v1.PredictionService` with methods like `Predict` and `RawPredict`, supporting both unary and streaming RPCs; for high-throughput scenarios, connection pooling and keep-alive settings (e.g., `grpc.keepalive_time_ms`) are critical to avoid connection churn. A real-world example is a real-time fraud detection system where sub-100ms latency is required—gRPC's binary framing avoids JSON parsing overhead and reduces CPU usage on both client and server.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
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FAQ
Questions learners often ask
What does this PMLE question test?
Serving and Scaling Models — This question tests Serving and Scaling Models — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: gRPC API — gRPC API is recommended for high-throughput, low-latency online prediction requests to Vertex AI endpoints because it uses HTTP/2 for multiplexed streaming, binary serialization (Protocol Buffers), and supports bidirectional streaming, which reduces latency and improves throughput compared to REST. Vertex AI's prediction service natively supports gRPC for real-time inference, making it the optimal choice for latency-sensitive applications.
What should I do if I get this PMLE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jul 4, 2026
This PMLE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PMLE exam.
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